1. Field of the Invention
The present invention relates to a capacitor-embedded substrate having a decoupling capacitor embedded in order to reliably compensate for fluctuation of a power source voltage.
2. Description of the Related Art
Conventionally, when semiconductor devices of the form of a chip, such as ICs, LSIs, super LSIs, and CPUs using these devices, are mounted on a mounting substrate such as a printed wiring substrate, there has been known to use, as the mounting substrate, a capacitor substrate having a surface on which a decoupling capacitor for preventing malfunction of a semiconductor device due to fluctuation of a power source voltage is formed (for example, see Japanese Patent Application Publication No. 6-318672).
In addition, there has been proposed an interposer-typed capacitor-embedded substrate having a high capacitive decoupling capacitor embedded therein, which is provided between a mounting substrate and a semiconductor element (for example, see Japanese Patent Application Publication No. 2001-358248).
Recently, as one of various high performance components, a high performance capacitor-embedded substrate in which the fluctuation of the power source voltage can be reliably compensated for has been demanded.
In recent semiconductor devices, efforts to achieve high density and high speed in addition to downsizing and high performance have been made. According to the downsizing and the high performance of the semiconductor device, higher operational frequencies, for example, a high frequency band of more than GHz, have been used.
However, in the conventional capacitor-embedded substrate, the decoupling capacitor is coupled to a power supply terminal and so on through wiring lines in the unit of mm in a horizontal direction perpendicular to a thickness direction. Accordingly, since the decoupling capacitor is affected by the length of the wiring lines in the high frequency band of, particularly, more than GHz, inductive components due to the length of the wiring lines cannot be ignored. Such inductive components make the decoupling capacitor difficult or even impossible to fulfill its function. Accordingly, the conventional capacitor-embedded substrate has a problem in that the fluctuation of the power source voltage cannot be reliably compensated for.